The present invention relates to a rotating anode X-ray tube capable of discharging intense heat generated when X-rays are generated.
Conventionally, there has been a rotating anode X-ray tube as shown in FIG. 4. In this rotating anode X-ray tube 50, X-rays 53 are generated from a target 52 when an electron beam 51 is applied from a cathode (not shown) to the target 52 in a vacuum. At the same time, most of the kinetic energy of the electron beam 51 is transformed into heat, causing an intense heat in the target 52. The heat of this target 52 is directly discharged outwardly of a vacuum tube 55 by radiation from the target 52 and a rotor 54 and is also discharged to the outside by heat conduction via a shaft 56, bearings 57 and a bearing housing 58.
However, in the above prior art rotating anode X-ray tube 50, the heat of the shaft 56 is conducted from the shaft 56 to the bearing housing 58 through only very small surfaces of contact between a race and balls 59 of the bearings 57, and this has led to the problem that the heat of the shaft 56 does not efficiently escape.
As described above, the inefficient escape of the heat of the shaft 56 has led to the problem that the cooling of the target 52 connected to the shaft 56 becomes insufficient to enable the increase in output power of the X-rays 53 and the continuous operation of the X-ray tube.
Furthermore, the inefficient escape of the heat of the shaft 56 has also led to the problem that the shaft 56 and the bearings 57 put in contact with the shaft 56 come to have an elevated temperature to impair the capability of the solid lubricant in the bearings 57 and extremely reduce the operating life of the bearings 57.